Bridge type piezoelectric pickup for stringed instruments

ABSTRACT

A BRIDGE TYPE PEIZOELECTRIC PICKUP FOR A GUITAR OR SIMILAR STRINGED INSTRUMENT COMPRISES A PLURALITY OF PIEZOELECTRIC OF PIE ZOELECTRIC ELEMENTS, ONE FOR EACH STRING, LOCATED WITHIN AN OPEN TOPED CASE. OVERLYING EACH OF THESE PIEZOELECTRIC ELEMENTS IS A RESPECTIVE ONE OF A PLURALITY OF SADDLE MEMBERS WHICH IS RESTRAINED TO VERTICAL SLIDING MOVEMENT RELATIVE TO THE CASE, EACH SADDLE MEMBER ENGAGING AND SUPPORTING ITS ASSOCIATED STRING AND TRANSMITTING VIBRATIONS FROM THE   STRING TO ITS ASSOCIATED PIEZOELECTRIC ELEMENT. THE PIEZOELECTRIC ELEMENTS HAVE TOP AND BOTTOM OUTPUT FACES INCLUDING METALLIC COATINGS. OUTPUT SIGNALS ARE EXTRACTED FROM THE ELEMENTS BY MEANS OF CONDUCTORS SOLDERED TO THE METALIC COATINGS TO FROM SOUND MECHANICAL AND ELECTRICAL CONNECTIONS BETWEEN THE CONDUCTORS AND THE ELEMENTS.

Jan. 23, 1973 BRIDGE -TYPE PIEZOELE'GTRIC 'PICKUP FOR STRING ED INSTRUMENTS Filed Dec. 6, 1971 3 Sheets-Sheet 1 FIG. I

J. H. RIOKARD 3,712,951

Jan. 23, 1973 J. H. RICKARD 3,712,951

BRIDGE TYPE PIEZOE'LECTRIC PICKUP FOR STRINGED INSTRUMENTS Filed Dec. 6, 1971 FIG. 3 5

3 Sheets-Sheet 2 Jan 23, 1973 J. H. RICKARD 3,712,951

BRIDGE TYPE PIEZOELECTRIC PICKUP FOR STRINGED.'INSTRUMENTS Filed Dec. 6, 1971 3 Sheets=$het 3 42J 40 42 J 4o 42 5O 5O 42 mm 4 Arm;

United States Patent U.S. Cl. 84-1.14 18 Claims ABSTRACT OF THE DISCLOSURE A bridge type piezoelectric pickup for a guitar or similar stringed instrument comprises a plurality of piezoelectric elements, one for each string, located within an open topped case. Overlying each of these piezoelectric elements is a respective one of a plurality of saddle members which is restrained to vertical sliding movement relative to the case, each saddle member engaging and supporting its associated string and transmitting vibrations from the string to its associated piezoelectric element. The piezoelectric elements have top and bottom output faces including metallic coatings. Output signals are extracted from the elements by means of conductors soldered to the metallic coatings to form sound mechanical and electrical connections between the conductors and the elements.

BACKGROUND OF THE INVENTION This invention relates to electrical pickups for transducers for stringed musical instruments, and deals more particularly with such a pickup which also acts as the bridge for the instrument and uses piezoelectric elements as the basic transducer means.

Electrical pickups or transducers are commonly used with many different types of musical instruments for converting the mechanical vibrations of the instruments to electrical signals which in turn may be amplified, and sometimes otherwise modified, and reproduced through a loud speaker to provide a louder and perhaps controllably distorted version of the sound produced by the instrument. The present invention relates to a pickup especially designed for use with stringed instruments such as guitars and for use where it is desired to have the amplified version of the musical performance match as closely as possible, except for loudness, the unamplified version as produced by the instrument itself. For example, guitars at present are often grouped into two different kinds, the first being acoustic guitars intended to be played without any electrical amplification, and the other being electric guitars designed especially for electrical amplification. Commonly, the amplified sounds made by electric guitars are quite different in character from those produced by an acoustic guitar. The pickup of this invention is one which lends itself well to use with an acoustic guitar, producing a hybrid kind of guitar, to enable the production of an amplified sound closely similar to that of the acoustic guitar as played by itself.

When it is desired that the pickup of a stringed instrument produce electrical signals as faithfully reproducing as possible the vibrations of the strings, it is commonly thought desirable to incorporate the transducer into the bridge of the instrument so that the vibrations which are normally transferred through the bridge to the instrument body are also passed through or exerted on the transducer element or elements, and various different such bridge type pickups have been proposed in the past, most of them involving the use of piezoelectric elements as the basic transducer means. Most of these pickups have, however, been difficult and expensive to manufacture and for reasons such as mechanical cross-coupling between 3,712,951 Patented Jan. 23, 1973 the piezoelectric elements for the various strings and poor electrical contact between the piezoelectric elements and the output conductors have not produced completely satisfactory results.

The general object of this invention is to provide an improved bridge type piezoelectric pickup for a guitar or similar stringed instrument which is capable of being simply and economically made and which produces output signals very faithfully representing the mechanical vibrations of the strings. Other desirable features and objects of the invention include construction of the pickup to produce a shielding effect reducing hum and other extraneous noise signals; a pickup construction which is readily made as either a flat bridge, as used for example with a classic guitar, or a rounded bridge, as used for example with a steel string guitar; a pickup construction wherein the individual string lengths are readily changed to adjust intonation; a pickup construction wherein the outputs from the piezoelectric elements for the various strings may be connected together to form a single output or may be brought out separately so as to allow the signal for each string to be treated separately from the signals for the other strings; a pickup construction wherein the danger of malfunction or distorted signal as a result of loose or poor connections between the piezoelectric elements and the output conductors are eliminated; and a pickup construction wherein the vibration of each string is transmitted directly to its associated transducer element with little or no influence on the transducer elements of the other springs so that mechanical cross-coupling effects between the strings are minimized.

SUMMARY OF THE INVENTION This invention resides in a bridge type piezoelectric pickup for a guitar or similar stringed instrument and comprising an open topped U-shaped case having a bottom wall and two vertical side walls. A plurality of piezoelectric elements equal in number to the number of strings of the instrument are located between the side walls and have top and bottom faces of opposite polarity, the top faces of all of said elements being of one polarity and the bottom faces of the other polarity. Above each piezoelectric element is a saddle member which engages the top surface of the element and which has two parallel side walls which slidably engage the side walls of the case to restrain it to vertical movement, the top portion of the saddle member engaging and supporting the associated string so as to transmit the string vibrations to the piezoelectric element. Conductor means engage the top and bottom faces of all of the elements to extract output signals therefrom, and preferably this conductor means includes a least one flexible wire extending either under the bottom faces of said elements or over the top faces of said elements and mechanically joined to such faces by a quantity of solder, the faces involved with the solder being provided with a metallic coating to which the solder adheres. When it is desired to combine the outputs from all of the strings, the conductor means still more preferably includes two wires one extending across the top faces of the elements and the other extending across the bottom faces of the elements with both of said wires being mechanically joined by solder to the faces which it contacts and with the faces including metallic coatings to which the solder adheres. The wire is preferably a very flexible wire such as one made of braided filaments so as to reduce the transmission of mechanical vibrations from one piezoelectric element to the other through such wire and preferably the case is made of aluminum or other electrical conductor and the top faces of the elements are connected to the case through the conductor means so as to be of the same potential as the ease and to thereby provide a shield effectively isolating the elements from extraneous signals.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary perspective view of the top plate or soundboard of a guitar showing a bridge type piezoelectric pickup embodying this invention.

FIG. 2 is an enlarged top view of the pickup of FIG. 1.

FIG. 3 is an elevational view on the same scale as FIG. 2 showing the pickup of FIG. 1.

FIG. 4 is a fragmentary vertical sectional view taken on the line 4-4 of FIG. 2.

FIG. 5 is a transverse sectional view taken on the line 5-5 of FIG. 3.

FIG. 6 is a transverse sectional view taken on the line 66 of FIG. 3.

FIG. 7 is an enlarged transverse sectional view taken through one of the piezoelectric elements of the pickup of FIG. 1 with the thickness of the metallic coatings of said element being exaggerated for the purpose of illustration.

FIG. 8 is a top view of the assembly of piezoelectric elements used in the pickup of FIG. 1.

FIG. 9 is a side elevational view of the assembly of FIG. 8.

FIG. 10 is a transverse sectional view taken on the line 1010 of FIG. 2 and additionally showing the pickup connected to a cable for transmitting the signals produced thereby to other parts located within the instrument body.

FIG. 11 is a side elevational view of an assembly of piezoelectric elements for use in place of the assembly of FIGS. 8 and 9 to produce a pickup comprising another embodiment of this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning first to FIG. 1, this figure shows fragmentarily a guitar 14 which is basically of the acoustic type and which includes a body having a top plate or soundboard 16. Attached to the upper surface of the soundboard is a combined bridge and tailpiece assembly 18 which serves both the tailpiece function of anchoring the lower ends of the strings 20, 20 to the remainder of the guitar and the bridge function of vertically supporting the strings and of transferring their vibrations to the soundboard 16. In particular, the assembly 18 is comprised of a tailpiece member 22 made of natural or resin impregnated wood or other material and an electrical bridge type pickup 24 which embodies this invention and which is received in a complementary notch 26 formed in the tailpiece 22.

As explained hereinafter, the electrical pickup 24 has electrical conductors on which the output signals produced by it appears, and preferably these conductors are connected inside of the guitar body to a cable which connects them to other parts of the electrical system also carried by the guitar, these including, for example, a volume control having a manually adjustable knob 28 and an output jack 30 through which the signals may be transmitted by another cable 32 to associated amplifying and sound reproducing equipment.

FIGS. 2 to 10 show the pickup 24 of FIG. 1 in more detail. Turning to these figures and first considering FIGS. 2, 3 and 5, the pickup comprises an open topped elongated U-shaped case 34 having a horizontal bottom wall 36 and two vertical parallel side walls 38, 38 which extend upwardly from the bottom wall to form an open topped channel therebetween. The case may be made of various different materials, either electrically conducting or electrically insulating, but preferably it is made of an electrically conducting material so as to act as part of an electrical shield for the parts received within it. Conveniently it consists of a section of an aluminum extrusion.

Contained within the channel of the case 34 is a plurality of piezoelectric elements 40, 40 which are part of a subassembly shown in FIGS. 8 and 9. As shown in the latter two figures, the piezoelectric elements 40, 40 are each of the thickness expander type which generates an electrical signal in response to forces applied across its thickness mode. That is, each element 40 has a top face 42 and a bottom face 44 and an electrical signal is generated across said top and bottom faces in response to changes in the force transmitted between such faces. As shown in FIG. 7 each piezoelectric element 40 has its top and bottom faces 42 and 44 coated with a metallic material such as silver. It is common to apply metallic coatings, such as those shown at 46, 46, to the faces of piezoelectric elements for the purpose of enhancing the electrical contact between the element and electrodes which are usually pressed against such faces, and various different means for producing such coatings are well known in the art. In accordance with one aspect of this invention, however, electrical connections with the piezoelectric elements 40, 40, are made by soldering conductors to the top and bottom faces, so as to provide rigid mechanical connections which make use of the metallic coatings, rather than to rely on connections made by mere pressure of electrodes against the faces.

In making the subassembly shown in FIGS. 8 and 9 the piezoelectric elements 40, 40 are arranged so that all of their top faces 42, 42 are of one piezoelectric polarity and so that all of their bottom faces are of the opposite piezoelectric polarity. In addition to the individual elements 40, 40, the subassembly includes a first conductor in the form of a wire 48 which passes across and engages the top faces 42, 42 of each of the elements 40, 40 and which is mechanically connected to each of such top faces by a quantity of solder 50. Additionally, a second conductor in the form of a wire 52 extends across and engages the bottom faces 44, 44 of the elements 40, 40 and is mechanically connected to each of such bottom faces by a quantity of solder 54. To reduce mechanical cross-coupling from one element to another by vibrations transmitted by the wires 48 and 52 these wires are preferably quite flexible and limp and are each in the form of a braided wire made of a plurality of small filaments.

Returning to FIGS. 2, 3, 5 and 6, the piezoelectric elements 40, 40 are vertically supported in the case 34 by two elongated strips 56, 56 of electrical insulating material. These two strips are transversely spaced from one another so as to form a recess 58 therebetween through which the bottom wire 52 passes and within which recess the quantities 54, 54 of solder connecting the wire 52 to the bottom faces of the elements 40, 40 are received. The strips 56, 56 also include upwardly facing surfaces 60, 60 which engage the elements 40, 40 on opposite sides of the bottom wire 52. Preferably, the material from which the strips 56, 56 are made is one which, in addition to being an electrical insulator, is also one which is rigid and relatively dead as far as vibrations are concerned. That is, it is one which has a relatively high internal damping so as not to support vibration. Delrin is such a material and is presently preferred for the strips 56, 56.

Above each piezoelectric element 40 is a respective one of a plurality of saddle members 62a and 62b. Each saddle member 62a or 62b includes a bottom portion' As shown best in FIGS. and 6 each saddle member 62 includes a downwardly opening recess 64 which extends longitudinally thereof and which serves to receive the upper wire 48 and the quantities 50, 50 of solder used to attach said latter wire to the upper faces of the elements 40, 40. On opposite sides of the recess 64 each saddle member further includes a horizontal surface 66 which bears against the upper face of the associated element 40. Each surface 66 extends transversely of the case outwardly beyond the associated element 40 and spaced from each side of the element 40, as shown in FIGS. 5 and 6, each saddle 62 includes a downwardly extending leg providing a vertical side wall 68 which slidably engages the adjacent side walls 38 of the case. The side walls 68, 68 of the saddle in conjunction with the side walls 38, 38 of the case therefore restrain the saddle to vertical sliding movement relative to the case.

The saddle members 62, 62 each have two generally vertical side walls 70; 70 which at the bottom portions of the saddle members loosely slidably engage one another, the saddle members being placed end-to-end within the case. At each end of the case is an end member 72 having a head 74 with a vertical face 76 which slidably engages the outboard end wall 70 of the adjacent saddle member 62', and a post portion 78 which extends downwardly through an opening in the bottom Wall of the case, the two post portions 78, 78 being adapted to fit in corresponding openings of the tailpiece 22 and the top plate 16 of the guitar to properly locate the pickup relative to said latter parts.

As is well known, it is often desirable in a bridge for a guitar to provide a means for adjusting the individual string lengths so as to allow the different strings to maintain their proper intonations as they are stopped at different frets. In the illustrated pickup 24 this is accomplished by providing saddle members having differently shaped top portions. For example, as shown in FIG. 6, the illustrated saddle members 62b have top portions which are shaped so as to provide a string engaging ridge 80!) located in the same vertical plane as the longitudinal center line of the case. On the other hand, each saddle member 62a, as shown in FIG. 5, has its top portion shaped so as to define a string engaging ridge 80a which is located to one side of the center line of the case. When placed in the case 34, the saddle members 62a, 62a may further be placed therein so that their ridges 80a, 80a lie either to one side or the other of the case center line. Therefore, by using only two different shapes of saddle members, such as shown at 62a and 62b in FIGS. 5 and 6, three different string length positions may be obtained. Obviously, if further different string length positions are desired, other saddle members with other differently shaped top portions may be used. Also, in the illustrated bridge, and as best shown in FIG. 3, all of the saddle members used in the bridge are shaped so as to define string engaging ridges located at the same height above the case 34, therefore producing a so-called flat bridge. It will be obvious, that if desired the various saddle members may be also shaped so as to have string engaging ridges of different heights to produce a generally rounded type of bridge as commonly preferred, for example, for steel stringed guitars.

The saddle members 62, 62 may be made of various different materials, but preferably are made of a relatively non-resilient or rigid material which is dead with regard to the transmission of vibrations. That is, it is one which similar to that of the strips 56, 56 has a high internal damping so as not to support vibrations. At the present, Delrin is the preferred material for the saddle members.

The two strips 56, 56 are preferably adhered to the case 34 and to the bottom faces of the piezoelectric elements 40, 40 by a contact cement or other suitable adhesive. The other parts are held in assembly by cured silicon rubber 82 which fills substantially all of the voids between the strips 56, 56, the case 34, the piezoelectric elements 40, 40 and the saddle members 62, 62. In making the pickup the strips 56, 56 may first be glued to the case 36, and the subassembly of piezoelectric elements 40, 40 may then be glued to the strips 56, 56 and the end members 72, 72 put in place. Then a predetermined quantity of uncured silicon rubber in liquid state may be poured into the case, after which the saddle members 62, 62 are inserted in the case and held clamped against the piezoelectric elements 40, 40 until the silicon rubber has cured, the amount of silicon rubber poured into the case being that amount which is suflicient to fill all of the voids which would otherwise exist in the pickup between its various parts.

In order to reduce hum and other extraneous noise as much as possible, the upper faces 42, 42 of the piezoelectric elements are preferably at the same potential as the case 34, the case 34 and the upper faces 42, 42 therefore in combination forming an electrically conductive shield substantially surrounding the remainder of the piezoelectric elements and elfectively minimizing the pickup of extraneous signals by said elements. The means for connecting the upper wire conductor 48 and the associated upper faces 42, 42 to the case may take various different means, but in the illustrated and preferred case, includes a pin 84 inserted by a force fit through a hole in the bottom wall 36 of the case. This pin includes an upper portion extending beyond the bottom wall 36 to which the upper conductor wire 48 is soldered. The pin also includes a bottom portion extending below the bottom wall of the case to which the shield conductor 86 of a cable 88 may be connected. Also as shown in FIG. 10, the bottom conductor 52 at the end adjacent the pin 84 is covered by a piece of tubular insulation 90 and passes through a hole in the bottom of the case for connection with the center conductor of the cable 88 as at 92.

The cable 88 shown in FIG. '10 may be a transmission cable used for connecting the pickup 24 to other parts located inside the guitar, such as the volume control 28 and jack 30 of FIG. 1, and it will be noted from FIG. 10 that the connections may be readily made from outside of the guitar body by passing the cable 88 through an opening in the top plate 16. After the connections are made, the connection illustrated at 92 is covered with an insulating tape and the cable 88 pushed back through the opening 94 as the pickup is brought into place with the tailpiece 22.

In the pickup illustrated in FIGS. ll0 all of the bottom faces of the piezoelectric elements 40, 40 are connected in common to the bottom wire 52 so that the signal appearing between the two wires 48 and 52 is a signal representing a summation of the individual outputs from all of the piezoelectric elements. In some cases it may be desired to extract from the pickup a plurality of signals, each originating from a respective one of the strings of the instrument and its associated piezoelectric element. By doing this, the individual signals may be combined in a controlled manner by other electrical equipment so as, for example, to emphasize or de-emphasize the sound produced by any one or more strings. Such a pickup may be produced, for example, by using a subassembly of piezoelectric elements such as shown in FIG. 11 in place of the subassembly shown in FIGS. 8 and 9. Referring to FIG. 11, the illustrated subassem bly similar to that shown in FIGS. 8 and 9 and the parts thereof which are similar to those of FIGS. 8 and 9 have been given the same reference numerals and need not be redescribed. In place of the bottom wire 52 of FIG. 9, the FIG. 11 subassembly includes a plurality of bottom wires 90, 90 each of which is connected by a quantity of solder 92 to the lower face 44 of a respective one of the elements 40, 40. Beyond the end portion which is connected to its associated piezoelectric element 40, each wire 90 is provided with an electrical coating or sheath to prevent it from electrically contacting other piezoelec tric elements for wires adjacent which it may pass.

I claim:

1. A bridge type piezoelectric pickup for a stringed instrument, said pickup comprising a case having an elongated horizontal bottom wall and two vertical parallel side walls extending along and upwardly from said bottom wall to form an open topped channel therebetween, a plurality of piezoelectric elements equal in number to the number of strings with which the pickup is to be used supported in said channel and spaced from one another along the length thereof, said piezoelectric elements having top and bottom faces of opposite polarity, output conductor means electrically connected with each of said top and bottom faces of each of said elements for extracting electrical output signals from said elements, and a plurality of saddle members each associated with a respective one of said elements, each of said saddle members overlying its respective element so as to be vertically supported by said top face of said element, each of said saddle members further including a bottom portion located within said channel and having two horizontally spaced vertical side walls which respectively slidably engage said two side walls of said case and a top portion which projects upwardly beyond said channel and is adapted to supportingly engage the associated string of said instrument.

2. A bridge type piezoelectric pickup as defined in claim 1 further characterized by said piezoelectric elements being arranged so that all of said bottom faces are of one polarity and all of said top faces are of the opposite polarity, and said output conductor means comprising a first conductor extending longitudinally of said case and located above and engaging all of said faces of said elements and a second conductor extending longitudinally of said case and located below and engaging all of said bottom faces of said elements.

3. A bridge type piezoelectric pickup as defined in claim 2 further characterized by one of said first and second conductors being a wire, each of said faces of said elements engaged by said Wire including a metallic coating, and a quantity of solder mechanically connecting said wire to said metallic coating of each of said latter faces.

4. A bridge type piezoelectric pickup as defined in claim 3 further characterized by said wire being a flexible braided wire.

5. A bridge type piezoelectric pickup as defined in claim 2 further characterized by said first and second conductors each being a respective one of two wires, each of said top and bottom faces of all of said elements including a metallic coating, and a quantity of solder mechanically connecting each of said two wires to the metallic coating of each of said faces which it engages.

6. A bridge type piezoelectric pickup as defined in claim 1 further characterized by said piezoelectric elements being arranged so that all of said bottom faces comprise a first set of faces of one polarity and all of said top faces comprise a second set of faces of the opposite polarity, and said output conductor means comprising a first conductor extending longitudinally of said case and engaging all of said faces comprising one of said sets of faces and a plurality of other conductors each electrically connected with an associated one of said faces comprising the other one of said sets of faces.

7. A bridge type piezoelectric pickup as defined in claim 2 further characterized by said first conductor being a first wire, each of said top faces of said elements engaged by said first wire including a metallic coating, 2. quantity of solder mechanically connecting said first wire to said metallic coating of each of said top faces, and each of said saddle members including a downwardly opening recess extending longitudinally of said case through which recess said first wire passes and within which recess the quantity of solder connecting said first wire to the associated one of said piezoelectric elements is located, each of said saddle member further including two downwardly facing horizontal surfaces on opposite sides of said recess which surfaces engage said top face of said associated piezoelectric element on opposite sides of said first wire.

8. A bridge type piezoelectric pickup as defined in claim 7 further characterized by said case being made of an electrically conductive material, and means electrically connecting said first wire to said case so that said case and said top faces of said elements have the same electrical potential, and means electrically insulating said second conductor from said case.

9. A bridge type piezoelectric pickup as defined in claim 2 further characterized by said second conductor being a wire member, each of said bottom faces of said elements engaged by said wire member including a metallic coating, a quantity of solder mechanically connecting said wire member to said metallic coating of each of said top faces, and means providing an upwardly opening recess extending longitudinally of said case through which recess said wire member passes and within which the quantity of solder connecting each of said bottom faces to said wire member is located, said latter means also defining two upwardly facing surfaces on opposite sides of said recess which surfaces engage said bottom faces of said elements on opposite sides of said wire member.

10. A bridge type piezoelectric pickup as defined in claim 9 further characterized by said recess providing means constituting two elongated strips of material disposed in said channel and extending longitudinally of said case, said two strips being spaced from one another transversely of said case to define said recess therebetween.

11. A bridge type piezoelectric pickup as defined in claim 1 further characterized by said piezoelectric elements being arranged so that all of said bottom faces are of one polarity and all of said top faces are of the opposite polarity, each of said top and bottom faces of each of said elements having a metallic coating, said output conductor means comprising a first wire extending longitudinally of said case and located above and engaging all of said top faces of said elements and a second wire extending longitudinally of said case and located above and engaging all of said bottom faces of said elements, a quantity of solder mechanically connecting each of said wires to the metallic coating of each of said faces engaged by said wire, each of said saddle members including a downwardly opening recess extending longitudinally of said case through which recess said first wire passes and within which recess the quantity of solder connecting said first wire to said top face of the associated one of said elements is located, each of said saddle members further including two downwardly facing horizontal surfaces on opposite sides of said recess which surfaces engage said top face of said associated piezoelectric element on opposite sides of said first wire, two elongated bottom strips disposed in said channel and extending longitudinally of said case, said two bottom strips being spaced from one another transversely of said case to define an upwardly opening recess therebetween through which said second wire passes and within which latter recess the quantity of solder connecting said second wire to said bottom face of each of said elements is located, said two bottom strips further providing two upwardly facing surfaces on opposite sides of said latter recess which surfaces engage said bottom faces of said elements on opposite sides of said second wire.

12. A bridge type piezoelectric pickup as defined in claim 11 further characterized by said case being made of an electrically conductive material, and means electrically connecting said first wire to said case so that said case and said top faces of said elements have the same electrical potential, and said two bottom strips being made of an electrical insulating material.

13. A bridge type piezoelectric pickup as defined in claim 12 further characterized by said saddle members and said two bottom strips being made of Delrin.

14. A bridge type piezoelectric pickup as defined in claim 12 further characterized by said means electrically connecting said first wire to said case comprising a pin inserted through and electrically contacting said bottom wall of said case, said pin having a top portion extending upwardly beyond said bottom wall and electrically connected to said first wire and a bottom portion extending downwardly beyond said bottom wall.

15. A bridge type piezoelectric pickup as defined in claim 1 further characterized by each of said saddle members including two generally vertical end walls spaced from one another longitudinally of said case, said saddle members being arranged in said channel with their adjacent end Walls slidably engaging one another, and two end members caried by said case, said two end members being located respectively at the opposite ends of said case and each having a generally vertical wall which slidably engages the outboard end wall of the adjacent outer one of said saddle members.

16. A bridge type piezoelectric pickup as defined in claim 15 further characterized by each of said end members including a head portion located generally within said channel and defining said generally vertical wall thereof and also including a post portion which extends downwardly through and beyond said bottom wall of said case for use in attaching said pickup to another structure.

17. A bridge type piezoelectric pickup for a stringed instrument, said pickup comprising an elongated supporting means providing an upwardly facing supporting sur face, a plurality of piezoelectric elements equal in number to the number of strings with which the pickup is to be used, said piezoelectric elements having top and bottom faces of opposite polarity and being arranged so that all of said bottom faces comprise a first set of faces of one polarity and all of said top faces comprise a second set of faces of the opposite polarity, said elements being spaced from one another along the length of said supporting means and having their said bottom faces engaging said upwardly facing supporting surface, means movable 10 vertically relative to said upwardly facing supporting surface and located above and in engagement with said top face of each of said elements for transferring vibrations from each string of the instrument with which the pickup is to be used to the associated one of said elements, and electrical conductor means electrically connected with each of said top and bottom faces of each of said elements for extracting electrical output signals from said elements,

each of said faces comprising one of said sets of faces including a metallic coating, said conductor means including a wire extending longitudinally of said supporting means across said faces of said one set, and a quantity of solder mechanically connecting said wire to each of said faces of said one set.

18. A bridge type piezoelectric pickup as defined in claim 17 further characterized by each of said faces of the other of said sets of faces including a metallic coating, said conductor means including a second wire extending longitudinally of said supporting means across said faces of said other set, and a quantity of solder mechanically connecting said wire to each of said faces of said other set.

References Cited UNITED STATES PATENTS 2,222,057 11/1940 Benioff 84l.16 3,073,203 1/1963 Evans 84--1.16 3,137,754 '6/1964 Evans 84-1.16 3,301,936 1/1967 Carman et al 84-l.l6 3,396,284 8/1968 Scherer 841.16 3,453,920 7/1969 Scherer 841.16 3,519,721 7/1970 Martin et a1. 84l.'l6 X 3,530,228 9/1970 Scherer 841.16 X

RICHARD B. WILKINSON, Primary Examiner U. WELDON, Assistant Examiner U.S. Cl. X.R. 841.l6, DIG 24 

